Solid-state electrical cells

ABSTRACT

IN A SOLID-STATE ELECTRICAL CELL OF THE TYPE HAVING A COMPRESSED PELLET CONTAINING A CHARGE TRANSFER COMPLEX BETWEEN TWO ELECTRODES, THE PELLETS INCORPORATES A POLAR LIQUID, PREFERABLY WATER.

United States Patent 3,582,404 SOLID-STATE ELECTRICAL CELLS Ian D. Blackburne, 71 Grevillea Road, Ashgrove,'Queensland; Graeme C. Morris, 8 Ruskin St., Taringa East,

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with normal aqueous systems in which both electrodes are reactive, one producing anions and one cations. In the solid-state system only one type of ion, usually anions, is produced. The inactive electrode merely supplies car- Queensland; Lawrence E.-Lyons, 21 26 Moggill Road, 5 Kenmore, Queensland; and Robert G. Hoare, Gowrre if g z fi E, niiutrahze the Ions not dls Private Hotel, Canberra, Australian Capital Territory, 0 arge a ac 6 m New South Wales, Australia I All such prior solid-state cells have been characterized No Drawing. Filed Nov. 6, 1967, Ser. No. 680,950 by short circuit currents in the range from about 10* Claims priority, application Australia, Oct. 27, 1966, amps to 5 10 amps.

13,144/ 66 10 In the higher part of this range the currents tended to 1 1- C H0111! 11/00, 15/06 4 Cl drop very rapidly to lower values with aging of the cell. US. Cl. 136-83 almS It is an object of this invention to increase the shortcircuit currents of these solid-state cells very considerably and thus increase their useful range of application, ABSTRACT OF THE DISCLOSURE 15 and to provide cells in which the cell voltage remains In a solid-state electrical cell of the type having a commo o t t ith ti pressed pellet containing a charge transfer complex be- The invention is based on the discovery that in this type tween two electrodes, the Pellet Incorporates a Polar of cell the addition of a polar liquid, such as water, to the liquid, preferably water. 7 solid electrolyte pellet profoundly affects the properties of the cell, in particular by raising the short-circuit current available by a factor of the order of a thousand. This invention relates to what will be called solid- The invention therefore comprises a solid-state elecstate electrical cells. Such cells using as electrolyte charge trical cell of the type having a compressed pellet containtransfer complexes have been described, the complexes ing a charge transfer complex between two electrodes involving, on the one hand, iodine or tetracyanoquinodicharacterized in that the material of said pellet incorpomethane (TCNQ) and, on the other hand, one of several rates a polar liquid. The polar liquid is preferably water. organic electron donor substances. (Journal of the Elec- Some experimental results will now be given showing trochemical Society, vol. 114, No.4, April 1967, pages the effects of addition of water to various cells. In each 323-329: Chemical Engineering News, July 18, 1966, case the electrolyte pellets were made by dry-mixing the page 20.) p p constituents and pressing them at 4,000-8,000 lbs./ square In these prior cells, the solid electrolyte'in compressed inch pressure. Where there was more than one electrolyte pellet form is mounted between two electrodes. Electrocomponent, thecomponents were mixed in about equal chemical reaction proceeds between the electrolyte and quantities of weight. Electrodes in each case, unless otherone electrode, the other electrode is electrochemically inwlse stated, were magnesium. active and serves as an ohmic contact only. This contrasts Short- Voltage circuit Electrolyte (volts) current Comments 0.8 10 ,uA.9 After disiccation. (a) Iodine- 14 31 #A. After 2 minutes exposure to atmosphere.

1. 35 60-80 ma. 1 drop water added. Active electrode Al"..- 0. 83 60 149.. Dry. Active electrode Sn 0. 11 3. 3 a. Dry.

(b) Iodine 1.48 32 a. Dry.

1.60 150 ma. 1 drop Water added. 1.55 50 ma. After5miutes. Pyranthrone 48 5.4 ma. 5 minutes vacuum desiccation,

1. 50 200 ma. Second drop of water added. 1. 50 94 rna. After 4 minutes. (Active electrode A1) 0.86 1. 49 ma. Dry.

(0) Iodine 1. 60 #8 1. 50 a. 30 minutes ageing. Ina. ldrop water added. Di-bromo anthracene 45 ma. After 45 seconds.

(d.b.a.) 2. 5 ma. 30 minutes vacuum desiccation.

190 ma. Second drop of water added. 100 ma. After seconds.

((1) 1.2ma. Dry.

i 56 3% ma. gelyeral drops of water added.

. ma. one a ein 1.15 250 ma. Furtliervt rateg added.

80 ma. 3% minutes ageing.

(e) Iz-paraffin 0 0 Addition of water had no effect.

(f) 1.35 0.4;la. After desiccation.

(I). a. %2 mirntesc ageirilg.

. a. 11111018 9. Ianaphthalene 1.5 160 rile. 1dropWati a d zieii.

....... 45 ma. 9 minutes ageing.

(g) 1.10 10.6ua. After desiccation.

1. 25 12. 5 pant) Moist atmosphere. 1. 30 13. 5 a. 2 minutes ageing. l -rncthylene blue 1. 50 ma. 1 drop water added.

1.66 150 ma. 7minutes ageing. 1.58 150 ma. 20 minutes ageing.

(h) 1.25 20.5;ta. After desciccation.

1. 35 45 #2.. In moist atmosphere. lz-polyvinyl pyridine... 1. 60 90 ma. 1 drop Water added.

1.00 38 ma. 15 minutes ageing.

NOTE-1M1. microamps ma.: milliamps.

From the above examples it will be seen that addition of 1 drop (about 0.15 cc.) of water raises the short-circuit current spectacularly except in case (e) Where the electrolyte remained inactive, probably because the paraffin prevented any penetration. Cases (f) (g) indicate that while exposure to a moist atmosphere has some efiect, this is small compared to that caused by addition of liquid water.

The general pattern shown by cases (b)(c) (d)(f) (g) (h) indicates that ageing decreases the first affect of water addition, but the short-circuit current does not drop to anywhere near the dry current. Later further addition of water raises the current again and ageing returns it to a new value higher than the first aged value.

Case (g) is particularly favourable. The iodine-methylene blue electrolyte gives a high short-circuit current and a nearly constant voltage during ageing.

While water has been used as the additive in all the above examples, other polar liquids such as dimethylformamide or tetrahydrofuran may be used instead, and give similar results.

The active electrode may be aluminium, tin or zinc instead of magnesium, the voltage depending on the metal used, as is disclosed in the papers referred to above, and illustrated in Examples (a) and (b) above. The addition of polar liquid to the pellets has similar elfects, the metal of the active electrode not appreciably affecting the ratio of short circuit currents in dry and wet states.

The second electrode may be carbon or nickel or other highly conductive substance. As this electrode gives only ohmic contact, a wide variety of materials may be used.

What we claim is: g

1. A solid-state electrical cell of the type having a compressed electrolyte pellet containing a charge transfer complex and two conductive electrodes; one active and one inactive, contacting said pellet on either side thereof said charged transfer complex comprising a first compound selected from the group consisting of iodine and tetracyanoquinodimethane; a second compound selected from the group consisting of pyranthrone, di-bromo anthracene, naphthalene, methylene blue and polyvinyl pyridine, and a polar liquid.

2. The cell of claim 1 wherein the polar liquid is a member selected from the group consisting of water, dimethylformamide and tetrahydrofuran.

3. The cell of claim 1 wherein the initial short-circuit current of the cell is at least milliamps prior to the incorporation of the polar liquid.

4. The combination of claim 1 and a polar liquid introduced into said pellet; the cell being such that the ratio of short-circuit currents of the cell after introduction and before introduction of said polar liquid is at least :1.

References Cited UNITED STATES PATENTS 2,874,204 2/1959 Morehouse et al 136-100 2,905,740 9/1959 Smyth et a1 136-83 3,057,760 10/1962 Dereska et a1. l36-137 3,346,423 10/ 1967 Smyth et al. 136153 3,352,720 11/1967 Wilson et a1. 136-137 OTHER REFERENCES Herman et al., Tiny battery gives 1.5 volts, Chemical and Engineering News, pp. 20 and 21, July 18, 1966, copy in 136137.

DONALD L. WATTON, Primary Examiner US. Cl. X.R. 136137, 153 

